Blade mounting for impact cutters



March 4, 1969 R. A. FLORCZAK BLADE MOUNTING FOR IMPACT GUT'IERS FiledSept. 20, 1967 INVENTOR. Richard A. F lorczak s 5 E n 1 W l4asa i l Ea;

United States Patent BLADE MOUNTING FOR IMPACT CUTTERS Richard A.Florczak, Belleville, N.J., assignor to The Singer Company, New York,N.Y., a corporation of New Jersey Filed Sept. 20, 1967, Ser. No. 669,149

US. Cl. 112252 Int. Cl. Db 65/00; B26b 7/00, 3/00 5 Claims ABSTRACT OFTHE DISCLOSURE This disclosure relates to an impact cutter for sewingmachines and particularly to an improved cutter blade mounting whichpermits self-aligning of the cutter edge of the cutter blade with itscooperating ledger surface and also provides a resilient connectionbetween the cutter blade and its carrier.

Background of the invention Summary of the invention In accordance withthe present invention the novel blade mounting for the impact cutterincludes a block fixedly connected to the movable end of the cutter anda blade loosely connected to the block. The improved mounting isdesigned to provide:

(1) means adjacent the blade connection to the block so as to permitlimited blade deflection on operation of the cutter, or (2) a bladehaving an arcuate upper edge disposed in point contact with the block soas to permit the blade to pivot into alignment for full line cutting onoperation of said impact cutter, or (3) a blade mounting including bothof the features set forth above under items (1) and (2).

It is therefore an object of the present invention to provide animproved blade mounting for an impact cutter which overcomes the priorart disadvantages; which is simple, economical and reliable; which isself-aligning; which absorbs part of the shock of the striking force ofthe blade and permits limited blade deflection on operation of theimpact cutter; and which improves blade life and cutting eificiency.

Other objects and advantages will be apparent from the followingdescription of one embodiment of the invention and the novel featureswill be particularly pointed out hereinafter in the claims.

Brief description of the drawings This invention is illustrated in theaccompanying drawings in which:

FIGIIRE l is a head end elevational view of part of a sewing machineembodying the present invention.

FIGURE 2 is a view taken along line 2--2 of FIG- URE 1.

FIGURE 3 is an exploded perspective view of the improved blade mounting.

FIGURE 4 is a two positional view of the self-aligning feature of theimproved blade mounting.

Description of the invention The head end of a conventional sewingmachine is shown in FIGURE 1 embodying the present invention.

Patented Mar. 4, 1969 A needle bar 10 is journaled for endwisereciprocatory movement in a needle bar bushing 12 mounted in the head 14of the sewing machine. The lower end of needle bar 10 has an eye pointedneedle 16 connected thereto for reciprocation therewith to penetrateinto the bed 18 as part of the usual stitch forming operation. A presserbar bushing 20 is also mounted in the head and has a presser bar 22journaled therein at the lower end of which is connected a presser foot24 which coacts with a feed dog 26 disposed in the bed and actuated torise above the flat working surface 28 in timed sequence to feed thematerial being sewn in the machine.

An impact cutter 30, which may be of the pneumatic type as illustratedin FIGURES 1 and 2, is mounted adjacent to the head 14. The axis of thecutter 30* forms an angle of substantially with the flat working surface28 to define a line of inclination designated generally as 32. Aconventional air cylinder 34 has a spring returned piston (not shown)therein connected to a non-rotatable endwise movable blade-carrying bar36, the axis of which coincide with the axial line 32. The upper end ofair cylinder 34 has a tube 38 fixedly connected thereto so as to connectthe air cylinder to a suitable source of pressure air (not shown). Theair cylinder 34 is of conventional design and operates when air is fedthrough the tube 38 to drive the piston and the connected blade-carryingbar 36 downwardly with suflicient force to effect cutting after whichthe spring will restore the bar 36 and piston to the inoperative orretracted position.

The air cylinder 34 of the impact cutter is mounted behind the presserbar 22 by a mounting bracket 40 that is held in assembled position by aclamp bar 42 which acts to secure the bracket 40 to the needle barbushing 12 and the presser bar bushing 20, as illustrated in FIGURE 2. Aflange 44 is formed at the free end of bracket 40 and positioned to liein a plane perpendicular to the inclined axis 32. The flange 44 has ahole therein through which the blade-carrying rod 36 extends. Thefitting 'on the lower end of the air cylinder 34 is threaded to receivea nut 46 that is drawn up against a star washer 48 which in turn locksagainst the lower side of the flange 44 and secures the air cylinder 34in assembled position, as shown in FIGURE 1.

The blade-carrying bar 36 is octagonally shaped and slides endwise in acorrespondingly shaped opening (not shown) in the air cylinder 34 so asto be non-turnable relative to the longitudinal axis of the aircylinder. The lower end of the bar 36 is threaded, as at portion 50, toreceive a jam nut 52 prior to being threaded into a hole 54 of a block56. The jam nut 52 is turned down to lock the block 56 which isbifurcated to form a recess 58 which extends upwardly from the bottomthereof, in a plane perpendicular to the line of feed and the length ofthe feed dog 26. The recess 58 has a substantially flat base 60 fromwhich a front leg 62 and a rear leg 64 extends on either side thereof. Ablade 66 and a resilient member or pad 68, as illustrated in FIGURES 1and 3, are disposed in the recess 58 and secured by a pair of screws 70passing through holes in the front leg 62 and threaded into the rear leg64.

The blade 66 and the resilient pad 68 preferably have a combinedthickness that is substantially equal to the width of the recess 58. Theblade 66 is preferably placed adjacent the rear leg 64, and the pad 68placed adjacent the front leg 62. The blade 66 has generously sizedclearance apertures 72 through which the mounting screws 70 pass,thereby permitting the blade 66 to have a limited degree of freedom ofmovement within the recess 58, the freedom of movement being somewhatretarded by the resilient member 68.

The lower edge of the blade 66 is formed with a knife edge 74, while theupper edge 76 is arcuately shaped. The arcuate edge 76 abuts against thesurface 60 of the recess 58 and the clearance apertures 72 permit theblade 66 to rock on the surface 60' and thereby be completelyself-aligning, as is illustrated in FIGURE 4. The dotted representationshows the arcuate edge 76 in point contact with the base 60 at a generalpoint designated A. The point A may represent any point of contact priorto the knife edge 74 contacting the flat working surface 28. -If theblade 66 were to retain such a position the cutting action of the blade66 would be defective. Whenever the knife edge 74 does not make fullline contact with the flat working surface 28 the initial contact ofedge 74 will force the arcuate edge 76 to roll against the base 60 asthe blade 66 continues to decend until a point of contact, designatedgenerally B, is reached which represents the point at which the knifeedge 74 comes into full line contact with the working surface 28. Theapertures 72 are so large that the blade 66 is permitted to shiftinstantaneously from point A to point B without interference from thescrews 70. The pad 68 also does not interfere with the self-alignment ofthe blade 66.

As in operation of the conventional impact or guillotine cutter, thepresent impact cutter 30 is activated to drive the knife edge 74, of theblade 66 against the fiat working surface 28 to sever any material orthread lying on the surface. Depending on the source of pressure air theforce of the cutting action is usually much greater than that requiredfor any particular item being out. In the past this has resulted inexcessive wear of the blade and or the impact surface, requiring thefrequent replacement of either or both. The improved blade mounting ofthe present invention eliminates this problem and greatly extends thelife of both the blade 66 and that portion of the working surface 28upon which the blade comes into contact.

Instead of fixedly connecting the blade in the mounting block the blade66 has been loosely mounted thereto with the additional space in therecess 58 taken up by the resilient member 68 which, when the compactcutter 30 is actuated, will act as a shock absorber. When the knife edge74 of the blade 66 contacts the flat working surface 28 the strikingforce of the blade is great ly dissipated by the pad 68. Since the blade66 lies along the inclined axis 32 the ability of the blade 66 todefleet against the resilient member 68 is greatly enhanced. Thedeflection of the blade 66 absorbs most of the excess striking forcewithout interfering with the cutting action of the blade 66 or theself-aligning feature described hereinbefore.

The resilient member 68 may be made of any suitable material such asnatural or synthetic rubber (such as neoprene), or other plastic.

In summary, on actuation of the impact cutter 30 the knife edge 74 ofthe blade 66 will strike the working surface 28 to cut the thread ormaterial, guillotine fashion and as the blade 66 strikes the surface theresilient member 68 will permit blade deflection. Any small mountingmisalignments of either the air cylinder 34 or the blade 66 are providedfor by having the rounded or arcuate edge 76 of the blade 66 rock on thebase 60 of the recess to insure full line contact of the knife edge 74on the working surface 28.

It will be understood that various changes in the details, materials,arrangements of parts and operating conditions which have been hereindescribed and illustrated in order to explain the nature of theinvention may be made by those skilled in the art within the principleand scope of the invention as expressed in the claims.

Having thus set forth the nature of the invention, what is claimedherein is:

1. An improved cutter blade mounting for a sewing machine thread chainimpact cutter having a movable carrier and means for imparting operativeand retractive movements to said carrier, said improved cutter blademounting comprising:

(a) a block fixedly connected to one end of said movable carrier,

(b) a recess formed in the block,

(c) a cutter blade disposed in the recess of said block,

and having at least one aperture therein,

(d) at least one aperture formed in the block aligned with the recessand of smaller cross sectional area than the aperture formed in theblade, and

(e) a means loosely connecting said cutter blade to said block byextending through the apertures thereof to permit said blade to moverelatively to said block.

2. The combination claimed in claim 1 wherein:

(a) the recess has a substantially flat base,

(b) the edge of the blade adjacent the fiat base of the recess is formedarcuately to have a point contact with said base and adapted onoperation of the cutter to shift into aligned position for full linecutting by said blade.

3. The combination claimed in claim 1 wherein the cutter has an inclinedaxis and the blade mounting comprises:

(a) the recess of the block extended parallel to the axis of the cutter,

(b) the blade disposed in the recess substantially parallel to the axisof the cutter, and

(c) a means limiting blade deflection disposed in the recess on onesideof the blade.

4. The combination claimed in claim 3 wherein:

(a) the means permitting blade deflection disposed in the recess on thetop side of above the blade.

5. A blade mounting for a sewing machine impact cutter intermittentlyoperated against a flat surface comprising:

(a) a block fixedly connected to the cutter for actuation thereby,

(b) a recess formed in the block and having a substantially fiat base,

(0) a blade disposed in the recess,

(d) one end of the blade having a knife edge extending outwardly of theblock, and the other end of the blade arcuately shaped for point contactagainst the base of the recess,

(e) means loosely connecting the blade in the recess of the blockwhereby on operation of the cutter the striking of the blade against theflat surface Will cause shifting of the arcuate end thereof to permitfull line contact of the knife edge of said blade against the fiatsurface.

References Cited UNITED STATES PATENTS 42,397 4/1864 Peters et al 30-169876,789 1/ 1908 Erdmann 30-169 1,123,721 1/1915 Foster 112-252 2,747,5335/1956 Enos 112-252 3,250,237 5/1966 Myska 112-252 3,303,805 2/1967Steiner 112-252 HERBERT F. ROSS, Primary Examiner.

US. (:1. X.R. 30169, 275

